Well I heard from Colorfabb Support about my "styrofoam" like prints and they suggested printing with no fan. A result like that indicates the material is cooling too fast affecting adhesion. I also have the side and front of the printer covered up in cardboard while printing, just to prevent drafts and keep some heat in. The UMO is printing a BB-8 frame piece now and with no fan it looks to be doing really well. I still have few burn-looking spots in the print, perhaps where a blob forms and drops into the print? I'm using Orange nGen so its noticeable! It has a few hours left until done. I'm using the standard nozzle, not the ruby.

Meanwhile, my UM2+ was printing with 50% fan on it's pieces and after doing some testing on those pieces, they are sturdy but less fan will be a good improvement. I've set the fan to off now and had a piece printing overnight but this new spool had an awful tangle inside the spool itself! It must have been quite the show, the force on the filament cut the filament guide in half!

So...the UMO is 70% done and a new one is under way on the UM2+....I think I have that spool untangled some!

Two thoughts went into why the parts were low strength....adhesion (not printing hot enough) and infill.

The default infill Cura picked was Grid and I left that alone. That was my first mistake! Knowing the pros and cons of each infill, and better documentation on it from Ultimaker would've been really helpful. But with most things Cura, development is fast paced so documentation seems to lag behind. (Not a dig at them, just a general observation)

After doing some small part prints that tested basic strength between triangle and lines, using temps from 240 to 245, it was obviously to me that temp was too hot (Link to Ultimaker forum thread I started there). I got the first layer "waves" or "tidal waves" from the filament being way too hot. So temperature wasn't my problem for strength. And the models I was printing wasn't an ideal test for strength, since these test pieces were horizontal.

I decided to print a 50% version of the part I have been printing.

I printing it with triangle infill and at the suggestion of Colorfabb, I printed it at 235C (up from my standard 230).

Fan was off

235C was an interesting result. I didn't have a blobby nozzle and the print came out really nice

Strength wise, I was very impressed. These pieces had been break horizontally on layer lines previously. I have no way to rate the force I applied to the part but I can tell you, it is still intact despite my bending it around!

Over the past few days, I have been printing the full-size pieces using the 235C temp and triangle infill

I haven't done a destructive test yet...but just from applying some force around on these pieces, they are stronger

This current one is white and it seems like ANY white filament, it's always a challenge!

I am finding I have to push the temperature up 2C to perform well. I have a section of support that, for some reason, doesn't always do a good job "supporting". Two prints failed 4 hours in when the "prong" portions of the part fell off the support. Thankfully I had been monitoring the printing (I was home!) and aborted the print.

Making the temp 2C warmer seemed to improve the support structure. How and I...I am not really sure....but if it works....!

Since the wheel halves are threaded, when I had a severe tangle, the force of the filament being pulled split the first one apart! The filament literally sawed them apart.

I printed a new one in nGen and scaled them up to 101% to account for shrinkage to fit the bearing.

Since this was a small part, I had to enable the cooling fan. I had it set to 30% and 235C. The first layer looked a bit wavy but subsequent layers covered it up and the bottom layer wound up very smooth.

nGen does require a bit more thought to get good results. Larger parts want more heat and no fan. Smaller to mid-sized, you may have to experiment a little.

I'm not a big fan of white filaments but this nGen, once you dial in the correct settings, looks really nice!

I initially had another filament guide on the back left side of the machine (viewing from behind). That fell apart and so far, I have just run this one guide by itself. It's done a good job on one spool of nGen!